Conversion of hydrocarbon oils



July 5, 1938. K. swARTwooD CONVERSION OF HYDROGARBON OILS Fild Aug. 17, 1935 INVENTOR D w m W S H T E N N E K L, TORNEY Patented July 5, 1938 UNITED STATES PATENT OFFICE CONVERSION OF HYDROCARBON OILS Application August 17,

10 Claims.

This invention particularly refers to an improved process for the selective conversion of relatively low boiling and high boiling oils wherein the residual liquid conversion products are reduced to substantially dry coke at relatively high pressure and the vaporous products resulting from the coking operation are subjected to additional conversion in a high pressure reaction chamber of the system together with other vaporous conversion products of the process.

One of the features of the present invention resides in the provision for reducing the residual conversion products of the process to substantially dry coke in a zone of relatively high superatmospheric pressure, withdrawing the evolved vapors from the coking Zone, separating therefrom undesirable high boiling components and entrained heavy liquids, returning the latter to the colL'ng zone and subjecting the remaining vapors to additional conversion time at substantial superatmospheric pressure, I have found that this not only results in the production of denser coke of more uniform quality than that ordinarily produced by the coking of cracked residues at substantially atmospheric or low superatmospherc pressure but in addition materially increases both the quantity and the quality of the motor fuel components of the vaporous products resulting from the coking operation.

Another feature of the invention resides in the provisions for subjecting a hydrocarbon oil charging stock of relatively wide boiling range to distillation by introducing the same into a relatively low pressure vaporizing chamber to which heated products from a'cracking coil of the system are supplied, subjecting resulting vaporous components of the charging stock and vaporous conversion products either to fractionation or to conversion in the high pressure reaction chamber of the system, prior to fractionation, and subjecting the residual liquid conversion products and high boiling components of the charging stock remaining unvaporized in said vaporizing chamber to additional heating under non-Coking conditions and subsequent reduction to coke in the high pressure coking chamber.

In one embodiment, the invention comprises subjecting an oil of relatively low boiling charracteristics to conditions of cracking temperature and superatmospheric pressure in a heating coil, introducing the heated products into a reaction chamber also maintained at superatmospheric pressure wherein vaporous products are subjected to appreciable continued conver- 1935, Serial No. 36,611

sion, withdrawing the liquid conversion products from the reaction chamber and returning the same to the coking chamber, separately withdrawing vaporous conversion products from the reaction chamber and subjecting the same to 5 fractionation whereby their components boiling above the range of the desired final light distillate products of the process are condensed as reflux condensate, separating the reflux condensate formed by such fractionation into selected relatively low boiling and high boiling fractions, supplying low boiling fractions to said heating coil for further conversion, subjecting the high boiling fractions to independently controlled con-l version conditions of elevated temperature and superatmospheric pressure in a separate heating coil, introducing the resulting heated products into a reduced pressure vaporizing chamber, si-

multaneously supplying charging stock for the process, comprising a hydrocarbon oil of relatively Wide boiling range, to said vaporizing chamber lwhereby to effect vaporization of all but its high boiling components of a heavy residual nature, withdrawing vaporous components of the charging stock and vaporous conversion products from the vaporzing chamber, and subjecting the same to said fractionation, withdrawing highboiling liquids remaining unvaporized in said vaporizing chamber therefrom, quickly heating the same to a relatively high cracking temperature under non-coking conditions, and introducing the heated oil into a coking chamber maintained at substantially superatmospheric pressure wherein they are reduced to substantially dry coke,

withdrawing vaporous products evolved during the coking operation from the coking chamber,

and supplying the same to said reaction chamber wherein they are subjected to appreciable continued conversion.

As an alternative method of operation, which however is not to be considered equivalent to the above method of operation, the chamberl to which the charging stock and the heated products from said separate heating coil are supplied may be operated at a substantially superatmospheric pressure slightly above that maintained in the reaction chamber land the vaporous products from this Zone returned to the reaction chamber for continued conversion.

The accompanying diagrammatic drawing illustrates one specific form of apparatus embodying the above mentioned features of the inven- 4 tion. Various other features and advantages not previously mentioned will also be apparent with Vnace I6 of any suitable form, an-d the resulting reference to the drawing and the following description thereof.

Referring to the drawing, hydrocarbon oil of relatively low boiling characteristics is recovered from within the system and supplied, as will be more fully described, to heating coil I, wherein it is subjected to the desired conversion conditions of cracking temperature and superatmospheric pressure by means of heat supplied from furnace 2 of any suitable form. The resulting heated products are discharged from the heating coil through line 3 and valve 4 into reaction chamber 5, which is also maintained at a4 substantial superatmospheric pressure, wherein Vaporous and residual liquid conversion products f separate and wherein the latter are subjected to appreciable continued conversion.

In the case here illustrated the highly heated products from heating coil I are introduced into the lower portion of chamber 5 and their residual liquid components quickly separate from their vaporous components in this zone, the residual liquid being withdrawn from the lower portion of the chamber through line 6 and valve I to pump 8, b-y means of which they are supplied through line 9 and valve Iii to coking chamber II, while the vaporous products which pass upward through the chamber and are subjected to continued conversion during their passage therethrough are withdrawn from its upper portion and directed through line I 2 and valve I3 to fractionation in fractionator I4.

Simultaneous with the operation above described a hydrocarbon oil of relatively high boiling characteristics, also recovered from within the system, is supplied, as will be later more fully described, to heating coil I5 wherein it is subjected to independently controlled conversion conditions of cracking temperature and superatmospheric pressure, by means of heat supplied from a furheated products are discharged through line I'I and valve I8 into chamber IS.

Depending upon the other operating conditions of the process and other desired results, chamber I9 may be operated either at a substantial superatmospheric pressure, preferably somewhat higher than that maintained in reaction chamber 5, or at a substantially lower pressure than that maintained in the reaction chamber. Separation of the vaporous and residual liquid components of the heated products from the heating coil I5 is accomplished in vchamber III. When desired, charging stock, for the process, preferably cornprising a hydrocarbon oil of relatively high boiling characteristics, may be supplied to this zone by means of line 20, valve 2 I, pump 22, line 23, line 24 and valve 25, or the charging stock may, when desired, be supplied, all or in part, through valve k26 in line 23 to fractionatorl I4.l The former method of operation is preferred when the charging stock-contains any appreciable quantity of high boiling components unsuitable as cracking stock for heating coil I5. When the charging stock is supplied, as described, to chamber I9 it is subjected to substantial vaporization therein by direct contact with the highly heated products fromheating coil I5, whereby substantially all but its high-boiling components unsuitable for conversion in heating coil I5 are vaporized. The

vvaporous components of the charging stock together with ther vaporous conversion products from heating coil I5 may be removed from chamber I 9 through line 21 and directed, as desired, either through line 28, valve 29 and line I2 to of a pump or compressor for transferring the vaporous products from the vaporizing chamber to the reaction chamber. f

High boiling components of the charging stock and residual liquid components of the conversion products from heating coil I5 which remain unvaporized in chamber IS are withdrawn from the lower portion thereof through line 32 and valve 33 to pump 34, by means of which they are supplied through line 35 and valve 36 to heating coil 37. Heating coil'l and furnace 38, enclosing the same, altho illustrated in a conventional manner in the drawing, are preferably of such form that the heavy residual liquid supplied thereto is subjected to relatively high ratesof heating for a relatively short time, whereby it is quickly heated to a sulhciently high temperature to effect its subsequent reduction to coke without allowing it to remain in the heating coil for a suilicient length of time to permit any substantial formation and deposition of coke in this Zone. The highly heated residual liquid is discharged from heating coil 3l through line 39 and Valve 4G into coking chamber I I, wherein its reduction to substantially dry coke is accomplished.

Coking chamber I I is preferably operated at substantially the same or somewhat higher superatmospheric pressure than that employed in chamber 5 in order'to permit the introduction of vaporous products from the coking chamber into the reaction chamber without the use of a pump or compressor. The coke produced in chamber II may be allowed to accumulate within this zone, to be removed therefrom in any well known manner not illustrate-d after the chamber has been substantially iilled or its operation has been completed for any other reason. When desired a pluralitfvT of coking chambers may be employed, although only a single chamber is illustrated in the drawing, in order that the coking stage, in common with the rest of the system, may be operated continuously. Chamber II is provided with a suitable drain line 4I, controlled by valve 42, which may also serve as a means of introducing water, steamor other suitable cooling material into the chamber Vafter its `operation has been completed and after it has been isolated from the rest of the system, in order to hasten cooling and facilitate the removal of coke. Vaporous products evolved during the coking operation are vwithdrawn from the upper portion of chamber I I' and directed through line i3 and valve 44 into reaction chamber 5, wherein they commingle with thehighly heated products from heating coil I, or the vaporous components thereof, and are subjected therewith to appreciable continued conversion in the reaction chamber.

The components of the vaporous products, supplied, as previously described, to fractionator I4,

The latter are Withdrawn from the lower portion of fractionator i4 through line 45 and valve 46 to pump 41, by means of which they are supplied throughv line 48 and valve 49 to conversion in heating coil I5. The selected low boiling fractions of the reflux condensate may be withdrawn from any suitable intermediate point or plurality of points in the fractionator, provision bein-g made in the case here illustrated for directing the same through line 50 and valve 5l to pump 52, by means of which they are supplied through line 53 and valve 54 to conversion in heating coil l.

Fractionated vapors of the desired end boiling point are Withdrawn, together with uncondensable gas produced Within the system, from the upper portion of fractionator I4, and are directed through line 54 and valve 55 to condensation and cooling in condenser 56. The resulting distillate and gas pass through line 5'! and valve 58 to co1- lection and separationl in receiver 59. Uncondensable gas may be released from the receiver through line 50 and valve 5I. Distillate may be Withdrawn from receiver 59 through line 52 and valve 53 to storage or to any other desired further treatment. When desired, a regulated portion of the distillate collected in receiver 59 may be recirculated, by Well known means not illustrated, to the upper portion of fractionator i4 to serve as a cooling and refluxing medium in this zone for assisting fractionation of the vapors and to maintain the desired outlet temperature from the fractionator.

The preferred range of operating conditions which may be employed to accomplish the objects of the present invention in an apparatus oi the character illustrated and above described may be approximately as follows: The temperature employed at the outlet from the light oil heating coil may range, for example, from 900 to 1050 F., preferably with a substantially superatmospheric pressure at this point in the system, for example, from 200 to 300 pounds or more per square inch. The temperature employed at the outlet'from the heavy oil heating coil may range, for example, from 850 to 950 F. and a superatmospheric pressure of the order of 100 to 500 pounds, or thereabouts, per square inch is preferred at this point in the system. The residual liquid to be subjected to coking is preferably heated to a temperature measured at the outlet from the heating coil to which it is supplied of from 900 to i000 F., and as previously mentioned the heating conditions are preferably so controlled in this zone that no substantial formation and deposition of coke will occur prior to the introduction of the heated oil into the ooking chamber. The coking chamber is preferably operated at a superatmospheric pressure of from 150 to 300 pounds per square inch, and preferably this pressure is substantially equalized in the reaction chamber, although When desired a somewhat lower superatmospheric pressure may be employed in the reaction chamber. The chamber to which the heated products from the heavy oil heating coil are supplied may employ any desired pressure ranging from substantially the same or somewhat higher than that employed in the reaction cham- Y ber down to substantially atmospheric pressure.

The fractionating, condensing and collecting portions of the system may employ pressures subsible operations of the process of the present invention as it may be accomplished in an apparatus such as illustrated and above described, the charging stock, which is a topped crude of about 32 A. P. I. gravity, is supplied to the chamber to which the heated products from the heavy oil heating coil are supplied, and the vaporous products from this Zone, together with the vaporous conversion products from the reaction chamber, are subjected to fractionation and the resulting reflux condensate is separated into selected relatively low boiling and high boiling fractions. The high boiling fractions of the reiiux condensate are subjected in said heavy oil heating coil to an outlet conversion temperature of approximately 920 F. and a superatmospheric pressure of approximately 300 pounds per square inch is employed at this point of the system. The succeeding vaporizing chamber to which these products are supplied is operated at a superatmospheric pressure of approximately 50 pounds per square inch. Residual liquid from the vaporizing chamber is quickly heated in the heating coil to which it is supplied to an outlet temperature of approximately 950 F. and the heated oil is introduced into the coking chamber, which is maintained at a superatmospheric pressure of approximately 250 pounds per square inch. This pressure is substantially equalized in the succeeding reaction chamber to which the vaporized products from the coking chamber are directed. The low boiling fractions of the reflux condensate, which have a boiling range of approximately 385 to 650 F., are subjected in the light oil heating coil to an outlet conversion temperature of approximately 950 F. at a superatmospheric pressure of about 400 pounds per square inch, and the resulting highly heated products are introduced into the reaction chamber. The fractionating, condensing and collecting portions of the system are maintained at a superatmospheric pressure of approximately 50 pounds per square inch. This operation will produce, per barrel of charging stock, approximately 67% of motor fuel having an octane number of approximately '70 and approximately 72 pounds of coke of uniform quality and good structural strength, the remainder being chargeable principally to uncondensable gas.

I claim as my invention:

l. In a process for the conversion of hydrocarbon oils wherein a relatively low boiling hydrocarbon oil is subjected to conversion conditions of cracking temperature and superatmospheric pressure in a heating coil, the heated products introduced into a reaction chamber, maintained under cracking conditions of temperature and superatmospheric pressure, wherein vaporous and residual liquid conversion products separate and the vapors are subjected to appreciable continued conversion, the vaporous conversion products Withdrawn from the reaction chamber and subjected to fractionation for the formation of reflux condensate and the recovery of desirable v light distillate by condensation of the iractionatheated products from said separate heating coil' into a vaporizing chamber, wherein separation of theirvaporous and residual liquid components is accomplished, withdrawing vaporous products from the vaporizing chamber and introducing the same to the reaction chamber wherein they are' subjected to continued conversion, withdrawing non-vaporous residual liquid from said vaporizing chamber, quickly heating the same to a high conversion temperaturey under non-coking conditions, introducing the resulting highly heated residual liquid into a coking chamber operated at substantial superatrnospheric pressure, wherein it is reduced to coke, withdrawing vaporous products from the coking chamber and introducing the same into said reaction chamber, wherein they commingie with the vheated products from the rst mentioned heatingcoil and are subjected therewith to appreciable continued conversion.

2. In a process for th'e conversion of hydrocarbon oils wherein a relatively low boiling hydrocarbon oil is subjected to conversion conditions of cracking temperature and superatmospheric pressure in a heating coil, the heated products introduced into a reaction chamber, maintained under cracking conditions of temperature and superatmospheric pressure, wherein vaporous and residual liquid conversion products separate and the vapors are subjected toappreciable continued conversion, the vaporous conversion products withdrawn from the reaction chamber and subjected to fractionation for the formation of reiiux condensate and the recovery of desirable light distillate by condensation of the iractionated vapcrs, the reflux condensate separated into selected relatively low boiling and high boiling fractions and the low boiling fractions supplied to said heating coil for conversion, the improvement which comprises subjecting the high boiling fractions of the reflux condensate to independently controlled conversion conditions of cracking temperature and superatmospheric pressure in a separate heating coil, introducing the heated products from said separate heating coil into arvaporizing chamber, wherein separation of their vaporous and residual liquid components is accomplished, withdrawing vaporous products from said vaporizing chamber and subjecting the same to said fractionation, withdrawing non-vaporous residual liquid from said vaporizing chamber, quickly heating the same to a high conversion temperature under non-coking conditions, introducing the resulting highly heated residual liquid into a coking chamber operated at substantial superatmospheric pressure, wherein it is reduced to coke, withdrawing vaporous products from the coking chamber and introducing the same into said reaction chamber, wherein they commingle with the heated products from the first mentioned heating coil and are subjected therewith to appreciable continued conversion.

3. The process as dened in claim 2 further characterized in that hydrocarbon oil charging stock for the process is introduced into contact 751' stock forthe process is supplied to said vaporizing chamber and the vapors thereof withdrawn from the vaporizing chamber and subjected to said fractionation; l

6. A conversion process which comprises heating hydrocarbon oil to cracking temperature under pressure in a heating coil and thendischarging the same into a separating zone, separating vapors from unvaporized oil in the separating zone, simultaneousiy heating a lighter oil in a second coil to higher cracking temperature than the oil in the rst-named coil and subjecting resultant vapors to continued reaction ltime in a conversion zone maintained under cracking conditions of temperature and pressure, removing unvaporized oil from the separating Zone and -distilling the same to coke in a coking zone, removing vapors from the separating zone and from the coking zone and introducing the same to said conversion zone for cracking therein in admixture with the second-mentioned vapors, and fractionating and condensing the commingled cracked vapors from the conversion zone.

7. A conversion process which comprises heating hydrocarbon oil to cracking temperature under pressure in a heating coil and then discharging the same into a separating zone, separating vapors from unvaporized oil in the separating zone, simultaneously heating a lighter oil in a second coil to higher cracking temperature than the oil in the rst-named coil and subjecting resuitant vapors to continued reaction time in a conversion zone maintained under cracking conditions of temperature and pressure, removing unvaporized oil from the separating zone and distilling the same to coke in a coking zone, removing vapors from the separating zone and from the coking zone and introducing the same to said conversion zone for cracking therein in admixture with the second-mentioned vapors, fractionating the vapors from the conversion zone to form relatively heavy and light reflux condensates and supplying these condensates respectively to said iirst-named and second coils, and nally condensing the fractionated vapors.

8. The process as defined in claim 6 further characterized in that the coking and conversion zones are maintained under superatmospheric pressure of at least 150 lbs. per square inch.

9. A conversion process which comprises heating hydrocarbon oil to cracking temperature under pressure in a heating coil and then discharging the same intol a separating zone, introducing charging oil for the processto the separating zone, separating vapors from unvaporized oil in the separating zone, simultaneously heating a lighter oil in a second coil to higher cracking temperature than the oil in the first-named coil and subjecting resultant vapors to continued reaction time in a conversion zone maintained under cracking conditions of temperature and pressure, removing unvaporized oil from the separating zone and distilling the same to coke in a coking zone, maintaining the coking and conversion zones under superatmospheric pressure of at least 150 lbs. per square inch, removing vapors from the separating zone and from the coking zone and introducing the same to said conversion zone for cracking vtherein in admixture withvthe second-mentioned vapors, and iractionating and condensing the commingled cracked vapors from the conversion zone.

10. A conversion process which comprises heating hydrocarbon oil to cracking temperature under pressure in a heating coil and then discharging the same into a separating zone, introducing charging oil for the process to the separating zone, separating vapors from unvaporized oil in the separating zone, simultaneously heating a lighter oil in a second coil to higher cracking temperature than the oil in the first-named coil and subjecting resultant vapors to continued reaction time in a conversion zone maintained under cracking conditions of temperature and pressure, removing unvaporized oil from the separating zone and. distilling the same to coke in a, coking zone, removing vapors from the separating zone and from the coking zone and introducing the same to said conversion zone for cracking therein in admixture with the second-mentioned vapors, fractionating the vapors from the conversion zone to form relatively heavy and light refluX condensates and supplying these condensates respectively to said first-named and second coils, and nally condensing the fractionated vapors.

. KENNETH SWARTWOOD. 

